1. Field
The following description relates to a semiconductor device. The following description also relates to a display driver IC structure that reduces the chip size by using transistors suitable for voltage used for each circuit on the display driver circuit. For instance, the transistors may be suitable for high-voltage or half voltage usage.
2. Description of Related Art
In Thin-Film Transistor Liquid-Crystal Display (TFT-LCD) technology, a column driver is also called a source driver in the sense that it runs a source electrode of TFTs used in the display. For example, when a gate driver enters into an on-status by applying a pulse onto a TFT, the source driver assumes the role of applying a signal voltage onto a pixel through a signal line. Conventionally, an analog driver that directly applies the signal voltage of the analog video onto a display was generally used. However, more recently, a digital driver is often used to apply the signal voltage. Therefore, a source driver IC receives an image data signal and a control signal digitally through an intra-panel interface from a timing controller, generates suitable analog signals, and allows a user to watch generated images on the TFT LCD panel. As the panel requires high definition, slimness, and low power features, a corresponding driver IC requires a slim form factor while also having more channels and a speedy transmission rate.
A conventional Liquid Crystal Display (LCD) source driver IC implements a chip by producing a transistor with two kinds of voltages. The conventional LCD source driver IC uses the method of dual-gate oxidation for implementation. Dual-gate oxidation is used for the purpose of implementing a transistor with two kinds of voltages, specifically, high voltage and low voltage.
In such an example, hundreds and thousands of channels are formed for the purpose of driving a TV LCD display. In such a display, about 70% of the unit channel is composed of high voltage transistor components. Accordingly, the size of the unit high voltage transistor used is significant. In a case of a high voltage transistor, the thickness of a gate insulation layer or Thick Cox increases and the size of transistor increases in order to satisfy the breakdown voltage requirements of a device, compared to a low voltage transistor. Furthermore, in an example of a high voltage transistor, the presence of a low-concentration drift region to endure a high voltage is required to be increased. Therefore, the size of a high voltage transistor increases and the chip size greatly increases as well.
Thus, when a high voltage transistor, the size of which is larger compared with a low voltage transistor, is used for the manufacturing of the LCD source driver IC, a restriction in reducing the overall size of chip is great.